Plastic wrappings or holders are widely known and used due to their low cost. These wrappings can be applied by hand on sundry containers (cans, tins, containers, or the like.,) for a great number of products and materials but due to the high cost of production in the bottling industries for soft drinks, beers, drinking waters, or the like., it is not economically feasible to apply the wrappings by hand and therefore a package forming machine is required for the marketing of such products.
In the state of the art there are some container wrapping machines operating at high speed (at least 900 containers/minute), but it should be noted that currently in the market no low speed machine (500 containers/minute or less) having the features of the present invention. The following briefly describes operation of machines which work in a similar way to that described in the present invention.
The machine subject matter of U.S. Pat. No. 3,032,944 applies the wrapping by means of a rotary drum on which there are located a series of sliding jaws running on tracks. Their movement is controlled by means of a pair of cams, one each located on each side of the drum, and when the drum spins, the jaws slide, opening the carrier to be located on the cans.
U.S. Pat. No. 4,250,682 describes a machine also consisting of a rotary drum with jaws, although differing from the above in that the jaws only on one side slide while the opposite side jaws remain stationary. As in the prior machine the jaws open while the drum spins, thus opening the carrier to locate it on the tin.
In U.S. Pat. No. 3,383,823 is there described another machine for applying a carrier wherein a series of pins catch the carrier, and are separated to open it and locate it on the tins.
One further machine is described in U.S. Pat. No. 4,817,361 consist of two plates with double jaws provided in the periphery for taking the carrier band from a tray and by spinning the plates the carrier opens as said plates spin on an axis offset a certain angle with reference to the horizontal plane of the machine. In contrast to the present invention, this machine merely presents an incline, in the vertical plane, of the movement axis of the plates, while in the present invention there is an incline in the vertical plane, and one in the horizontal plane, which prevents the jaws from striking the containers during operation.
These machines have the disadvantages of being noisy, high production costs, relatively large sizes, complex maintenance and construction, very high operation speeds for some applications, difficult mechanical adjustments for different packages, as well as more working time for different size and diameter dimensions of the containers. The present invention describes a machine that judged by the inventors avoids these and other drawbacks.